Postoperative endophthalmitis is a feared albeit relatively rare complication of cataract surgery. The incidences reported in the two large studies discussed below were 0.06 and 0.17%, respectively. Infection by bacteria, primarily staphylococci and streptococci, can lead to legal blindness.
A large study was conducted in Sweden that involved 188,155 patients and addressed the question of the benefit of intracameral injection of antibiotics during cataract surgery. Wejde et al 2005 Acta Ophthalmol Scand 83: 7-10. The results of the study revealed a reduction of endophthalmitis by a factor of greater than 4 in patients that had received intracameral antibiotic. In 98.5% of cases, the antibiotic used was cefuroxime, which antibiotic is active against gram-positive bacteria. The remaining 1.5% received gentamycin and vancomycin. Gram-positive bacteria were the dominating aetiology in the endophthalmitis cases observed (84.6% proven by culture).
Results of a large study of the European Society of Cataract & Refractive Surgeons (ESCRS) were reported in 2007. J Cataract Refract Surg 33: 978-88. The study was carried out at 24 centers in 9 European countries and included 16,603 patients that underwent phacoemulsification cataract surgery with placement of an intraocular lens. The patients were assigned to four groups. Group A received no antibiotic prophylaxis. Group B received intracameral cefuroxime (1 mg in 0.1 ml of normal saline) at the end of surgery. Group C was administered levofloxacin drops prior and subsequent to surgery. Group D received both cefuroxime and levofloxacin. Twenty-nine patients experienced endophthalmitis. The study revealed that injection of cefuroxime reduced the risk for endophthalmitis by nearly five fold. Levofloxacin drops were essentially without effect.
These studies unambiguously demonstrated the considerable benefit of intracameral injection of cefuroxime. Although cefuroxime has been used widely in ophthalmic practice for about ten years, there are still no formulations and delivery systems available that were specifically designed or assembled for ophthalmic use. Cefuroxime has limited stability in aqueous solution, in which it hydrolyses at a rate of about 10% in 48 hours (at room temperature). Hence, practitioners currently have to purchase the drug as a bulk powder and have to dissolve and dilute the resulting solution down to the concentration appropriate for prompt intracameral injection. The above-mentioned ESCRS study followed a protocol comprising 16 individual steps for preparing an intracameral injection of cefuroxime. This “kitchen pharmacy” approach is highly inconvenient and time-consuming considering that the cataract procedure itself takes only about 7.5 minutes.